In rooms of offices, schools, or the like, a large number of lighting equipment typically having a straight tube shape are arranged at regular intervals in a grid pattern on the ceiling.
In such rooms, in control of the lighting equipment for efficient illumination suitable for occupancy statuses, power cannot be saved satisfactorily by merely turning off the lighting equipment near the seats of absentees.
In rooms of offices or the like, the illuminance necessary for an occupant is obtained not only from the light of one piece of lighting fixture but also from the overlapped light of a plurality of lighting equipment. When turning off a lighting fixture, accordingly, not only its influence on the seat positioned directly below this lighting fixture but also its influence on the adjacent seats is preferably taken into account.
For efficient illumination suitable for occupancy statuses, therefore, the brightness of each of a plurality of lighting equipment is adjusted through the cooperation among the plurality of lighting equipment.
In light control to adjust the brightness of the light, an illuminance sensor is typically used to perform light control based on the illuminance detected by the illuminance sensor (for example, see Patent Document 1).